This patch adds "tty-index" field to /proc/PID/fdinfo/N if N
specifies /dev/ptmx. The field shows the index of associative
slave pts.
Though a minor number is given for each pts instance, ptmx is not.
It means there is no way in user-space to know the association between
file descriptors for pts/n and ptmx. (n = 0, 1, ...)
This is different from pipe. About pipe such association can be solved
by inode of pipefs.
Providing the way to know the association between pts/n and ptmx helps
users understand the status of running system. lsof can utilize this field.
Signed-off-by: Masatake YAMATO <yam...@redhat.com>
---
drivers/tty/pty.c | 12 +++++++++++-
drivers/tty/tty_io.c | 14 ++++++++++++++
include/linux/tty_driver.h | 5 +++++
3 files changed, 30 insertions(+), 1 deletion(-)
diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index 66b59a1..4c8cf03 100644
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -674,6 +674,13 @@ static void pty_unix98_remove(struct tty_driver *driver,
struct tty_struct *tty)
}
}
+#ifdef CONFIG_PROC_FS
+static void pty_show_fdinfo(struct tty_struct *tty, struct seq_file *m)
+{
+ seq_printf(m, "tty-index:\t%d\n", tty->index);
+}
+#endif
+
static const struct tty_operations ptm_unix98_ops = {
.lookup = ptm_unix98_lookup,
.install = pty_unix98_install,
@@ -687,7 +694,10 @@ static const struct tty_operations ptm_unix98_ops = {
.unthrottle = pty_unthrottle,
.ioctl = pty_unix98_ioctl,
.resize = pty_resize,
- .cleanup = pty_cleanup
+ .cleanup = pty_cleanup,
+#ifdef CONFIG_PROC_FS
+ .show_fdinfo = pty_show_fdinfo,
+#endif
};
static const struct tty_operations pty_unix98_ops = {
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index e6d1a65..24a999d 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -106,6 +106,8 @@
#include <linux/kmod.h>
#include <linux/nsproxy.h>
+#include <linux/seq_file.h>
+
#undef TTY_DEBUG_HANGUP
#ifdef TTY_DEBUG_HANGUP
# define tty_debug_hangup(tty, f, args...) tty_debug(tty, f, ##args)
@@ -471,6 +473,15 @@ static int hung_up_tty_fasync(int fd, struct file *file,
int on)
return -ENOTTY;
}
+#ifdef CONFIG_PROC_FS
+static void tty_show_fdinfo(struct seq_file *m, struct file *file)
+{
+ struct tty_struct *tty = file_tty(file);
+ if (tty && tty->ops && tty->ops->show_fdinfo)
+ tty->ops->show_fdinfo (tty, m);
+}
+#endif
+
static const struct file_operations tty_fops = {
.llseek = no_llseek,
.read = tty_read,
@@ -481,6 +492,9 @@ static const struct file_operations tty_fops = {
.open = tty_open,
.release = tty_release,
.fasync = tty_fasync,
+#ifdef CONFIG_PROC_FS
+ .show_fdinfo = tty_show_fdinfo,
+#endif
};
static const struct file_operations console_fops = {
diff --git a/include/linux/tty_driver.h b/include/linux/tty_driver.h
index b742b5e..499823d 100644
--- a/include/linux/tty_driver.h
+++ b/include/linux/tty_driver.h
@@ -243,6 +243,7 @@
#include <linux/list.h>
#include <linux/cdev.h>
#include <linux/termios.h>
+#include <linux/seq_file.h>
struct tty_struct;
struct tty_driver;
@@ -285,6 +286,10 @@ struct tty_operations {
int (*set_termiox)(struct tty_struct *tty, struct termiox *tnew);
int (*get_icount)(struct tty_struct *tty,
struct serial_icounter_struct *icount);
+#ifdef CONFIG_PROC_FS
+ void (*show_fdinfo)(struct tty_struct *tty, struct seq_file *m);
+#endif
+
#ifdef CONFIG_CONSOLE_POLL
int (*poll_init)(struct tty_driver *driver, int line, char *options);
int (*poll_get_char)(struct tty_driver *driver, int line);
--
2.9.3
